Add New Items to Mirrored Column in a Monday.com board WITHOUT overwriting

Hello! We are using Monday.com CRM as our company database/project management tool. We have multiple boards available in the CRM including Jobs, Companies and Clients. What I want to do is ensure that every time a new job is added in the Jobs board, that Pulse ID/Job ID is then added to a mirror column called ‘Total Jobs’ on entry on the Companies or Clients board associated with the Company/Client on the new Job added. Basically we just want to see how many jobs each company/client currently has in our system.

I am trying to create a flow that works as follows:

Job is added to a Monday.board (Watch Board’s Items) → Get an Item’s Column Value (Find the Entry for the Company column) → Get an Item (Find the actual ID of that Company) → Search Items in Board (To find the associated ‘Total Jobs’ mirror column and return any entries in there) → Add the Pulse ID from the initial watch Board’s Items to the Total Jobs WITHOUT overwriting any IDs already in there.

I am struggling with working out how to do the final step in bold. Here is a screenshot of the
flow I have so far which is working perfectly fine but I just need help on the final step!